Electrical resistor



April 7, 1953 o. F. BOYKIN ET AL 2,634,352

ELECTRICAL RESISTOR Filed June 25, 1952 :lll/lill; lll/lll z i l E @if INVE" A T TURNE Y Patented Apr. 7, 1953 ELECTRICAL RESISTOR Otis F. Boykin, Chicago, and Hal F. Fruth, Skokie, Ill., assignors to Boykin-Fruth, Inc., Chicago, Ill., a corporation of Illinois Application June 23, 1952, Serial No. 295,055

This invention relates to electrical resistors and more particularly to wire type resistors.

Precision resistors as heretofore manufactured for electronic and other high frequency applications have been diiilcult to manufacture and hence quite expensive. Diiliculty has also been encountered in maintaining the inductive and reactive capacity effects of such resistors at a low value and in sealing and mounting the resistors for many types of difficult applications.

It is accordingly one of the objects of the present invention to provide an electrical resistor which is simple and inexpensive to manufacture, and which is easy to seal and mount.

Another object is to provide a resistor in which the inductive and reactive capacity effects are low, thereby to provide an inherently low time constant.

Another object is to provide an electrical resistor in which the resistance element is formed by an elongated wire wound into a skein.

According to one feature of the invention the sides of the skein are twisted or folded together to minimize the inductive edect of the resistor.

Another object is to provide an electrical resistor in which a skein of wire is enclosed in a housing with the ends of the wire connected to terminals projecting from the housing.

A further object is to provide an electrical resistor in which a skein of wire is wound on an insulating body which is then enclosed and sealed in a tubular housing. In the preferred construction the insulating body is tubular to receive a mounting bolt or the like and is threaded on its exterior to facilitate winding of the skein.

A still further object is to provide an electrical resistor in which a skein of wire is inserted in a. tubular housing and the ends of the wire are connected to terminals extending through closures in the ends oi the housing.

A still further object is to provide an electrical resistor in which the exterior surface of the body is threaded to receive mounting nuts or the like.

The above and other objects and advantages of the invention will be more readily apparent when viewed in connection with the accompanying drawing in which:

Figure 1 is a diagrammatic View illustrating a step in the manufacture of a resistor embodying the invention;

Figure 2 is a perspective view of a partially completed resistor;

Figure 3 is a similar view illustrating a subsequent step in the method of manufacture;

14 Claims. (Cl. 201-63) Figure 4 is a perspective view of a completed resistor with parts broken away and in section;

Figure 5 is a central section through an alternative form of resistor with parts in elevation;

Figure 6 is a perspective View of still another form of resistor partially completed;

Figure 7 is a perspective view showing the resistor of Figure 6 in completed form;

Figures 8 and 9 are sectional views showing stages in the manufacture of still another type of resistor, and

Figure l0 is a sectional view with parts in elevation illustrating one manner of mounting resistors embodying the invention.

According to the present invention resistors are formed by lengths of resistance Wire which is preferably relatively line wire on the order of .001 to .006 inch. Wires of these sizes are used for resistors of relatively small current ratings having values from .5 to 100,000 ohms, although for resistors of different current ratings larger or smaller wire sizes could be employed in the same way.

To form` the skein, wire is drawn from a spool indicated at l0 in Figure 1 onto a relatively large rotating mandril il which may be driven by a motor l2. Insulated wire is employed and the wire may if desired be further coated with wax, oil, or the like, by passing it through a wiper unit I3 between the spool and the mandril. Wire is wound onto the mandril until the necessary length of wire is present to produce the desired resistance value. When so wound the wire is cut off and slipped from the mandril in the form of a skein as indicated at i4 in Figure 2 with the ends of the wire projecting from the skein as shown at I5.

The skein of wire so formed is then folded upon itself or twisted or both so that the inductive effects in different sections of the wire will cancel each other. As shown in Figure 2 a iiexible insulating sheet I6 of plastic or like material may be inserted in the skein between the sides thereof to reduce the reactive capacity due to the small spacing between adjacent turns of the skein, although this is not essential in all types of resistors. The skein and sheet are then twisted together and folded as shown in Figure 3 into substantially a U-shape. The unit so formed either with or without folding may be housed in any desired type of housing and may have the wire ends I5 connected to suitable terminals to form a completed resistor.

In the construction shown in Figure 4 the twisted and folded skein with an insulating sheet I6 therein is embodied in a molded block I'l of insulating material such as a plastic. Terminals I 8 are provided projecting from the block and are preferably soldered or otherwise electrically connected to the wire ends I before the block is molded. The completed unit provides an extremely rugged resistor which can easily be handled without damage and which will accurately provide the desired resistance value with a minimum of inductive effect.

In the unit shown in Figure 5 the skein when completed preferably has its sides twisted upon each other either with or without an insulating sheet between them. The skein is then helically wound on an insulating body I9 which is prefer- :ably tubular to provide a passage 2l for a mounting bolt or the like. The exterior surface of the body I9 is preferably formed with spiral threads v22 in which the skein can be wound to hold the skein securely in place. After4 the skein is wound on the body the entire unit is slipped into .a tubular housing 23 formed of insulating material such as porcelain or plastic. The ends of the wire are connected mechanically or by soldering to terminals 2d shown as having circular ends to t into the ends of the housing 23 and soldering tabs projecting therefrom through notches in the end portions of the housing. The entire unit may be sealed by sealing material 25 such as solder,

cement or the like securing the ends of the body I9 to the ends of the housing 23. The solder or cement may t around and adhere to the terminals as shown so that the entire unit is tightly sealed against ingress of moisture or foreign materials. Where porcelain housing and body members are employed the end portions thereof may be coated which copper or other metals to facilitate soldering. This unit when completed is also a very rugged unit in which the desired resistance value can be accurately maintained with a minimum of inductive eect.

The unit shown in Figures 6 and 7 is a flexible type unit which is desirable for mounting in close and diicult places. As shown in Figure 6 the skein I@ is twisted without being folded and the wire ends I5 project from opposite ends thereof for connections to terminals. The terminals as shown at 26 may be formed of wire with hooks 21 at their ends to hook over the wire ends I5. Electrical connection may be established mechanically by squeezing the hooks 21 over the wire and if desired the joints may also be soldered. The terminals 25 are formed intermediate their ends with open loops 28 for mounting terminals in the housing. The unit so formedv may be slipped into a tubular iiexible housing 29 as shown in Figure 7 which may be formed of flexible plastic or of woven textile material as desired. To secure the unit in the housing and to relieve strain on the wire terminals I5 rivets or other fastenings as shown at 3| may be inserted through the end portions of the housing and through the open loops 28 of the terminals. rThis resistor when completed can be bent easily to t into difficult or confining spaces and will also provide accurately the desired resistance value with a minirnum inductive effect.

Figures 8 and 9 illustrate a button type resistor. In this construction the ends of the wire in the skein as shown at 32 are soldered or otherwise secured to wire terminals 33. The terminals A33 extend through end closure discs 34 and may be sealed therein by soldering or cementing as de.- sired` The skein itself is simply folded between the. end discs as illustrated. Y,

The 4assembly so formed is inserted in a relatively short tubular housing 35 and the discs 3d may be secured therein by spinning the ends of the housing over as indicated at 36. It will be apparent that instead of or in addition to the spinning, soldering or cementing to secure or seal the discs in place could be used. The completed resistor is an extremely small, compact unit which can easiiy be mounted in confined places and which will accurately provide the desired resistance value with a minimum inductive effect.

Figure l0 illustrates still another form of resistor in which the skein shown at 31 may be twisted or folded together to fit into an elongated tubular housing 38 which is preferably of insulating material such as porcelain. The ends of the wire are soldered or otherwise secured to terminals S9 which extend through closure plugs 4I and may be sealed thereto by soldering or cementing. The closure plugs di i'lt tightly into the ends of the housing and may be secured and sealed therein by soldering or cenienting.

To mount the unit, the exterior of the body 38 is threaded as indicated at 42 to receive mounting nuts d6. The unit may be inserted through an opening in a chassis or other mounting plate shown at iii and the nuts 43 may be tightened against the plate to secure the resistor in place.

In all of theunits, it will be noted that the resistance is provided by an elongated wire whose length can be accurately controlled to control the resistance value and which can be twisted or folded in the form of a skein to neutralize inductive effects. In each of the units of Figures 5 through l0 wherein the Askein is mounted in a housing, the housing may be lled fully or partially with a silicone varnish, a grease or like iilling material to increase resistance of the unit to humidity and to hold the skein hrmly in place in the tube.

While several embodiments of the invention have been shown and described in detail herein, it will be understood that they are illustrative only and are not to be taken as a definition of the scope of the invention, reference being had for this purpose to the appended claims.

What is claimed is:

l. An electrical resistor comprising an elongated wire wound into a skein, the sides of the skein being folded together to minimize inductive effects, and the ends of the wire projecting from the skein as terminals.

2. An electrical resistor comprising an elongated wire wound into a skein, an insulating sheet between the sides of the skein, the skein and sheet being twisted together to minimize inductive effects, and the ends of the wire projecting from the skein as terminals.

3. An electrical resistor comprising an elongated wire wound into a skein, the sides of the skein being twisted together to minimize inductive eiects, and the ends of the wire projecting from the skeins as terminals.

4. An electrical resistor comprising an elongated wire wound into a skein, the skein being folded upon itself to minimize inductive effects, and the ends of the wire projecting from the skein as terminals.

5. An electrical resistor comprising an elongated wire wound into a skein, the sides of the skein being twisted together and then folded upon themselves toA minimize inductive. effects, and the ends of the wire projecting from the skein as terminals.

6. An electrical resistor comprising an insuf lating housing, an elongated wire wound into a skein in the housing, and terminals projecting beyond the housing and electrically connected to the ends of the wire.

'7. An electrical resistor comprising an insulating housing, an elongated Wire wound into a skein in the housing, and terminals projecting beyond the housing and electrically connected to the ends of the wire, the sides of the skein being twisted together in the housing to minimize inductive effects.

8. An electrical resistor comprising an insulating housing, an elongated wire wound into a skein in the housing, and terminals projecting beyond the housing and electrically connected to the ends of the wire, the skein being folded upon itself in the housing to minimize inductive eiects.

9. An electrical resistor comprising an elongated insulating body, an elongated wire Wound into a skein, the skein being Wound helically on the body, a tubular housing tting over the body and the skein, and terminals projecting beyond the housing and connected to the ends of the wire.

l0. An electrical resistor comprising an clongated insulating body, an elongated wire wound into a skein, the skein being Wound helically on the body, a tubular housing tting over the body and the skein, and terminals projecting beyond the housing and connected to the ends of the wire, the ends of the tubular housing being sealed to the body and terminals completely to enclose the skein.

11. An electrical resistor comprising an elongated tubular body threaded on its exterior, an elongated Wire Wound into a skein, the skein being helically Wound in the threads on the body, a tubular housing tting over the body and sealed to the body at its ends to leave the opening through the body unobstructed, and ter minals extending from the housing and connected to the ends of the wire.

12. An electrical resistor comprising a tubular insulating housing, an elongated wire wound into a skein tting in the housing, closure mem bers tting into the ends of the housing and having openings therethrough, and terminals extending through the openings and connected to the ends of the Wire.

13. An electrical resistor comprising a tubular insulating housing, an elongated wire wound into a skein tting in the housing, nat closure discs tting in the ends of the housing and formed with openings therein, and terminals eX- tending through the openings and secured to the ends of the wire.

14. An electrical resistor comprising a tubular insulating housing, an elongated wire wound into a skein fitting in the housing, terminals extending from the ends of the housing and connected to the ends of the wire, the exterior' of the housing being threaded to receive nuts by which the resistor is mounted.

OTIS F. BOYKIN. HAL F. FRUTH.

No references cited. 

